/*
 * Copyright (C) 2012-2017 DataStax Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.datastax.driver.core;

import com.datastax.driver.core.exceptions.CodecNotFoundException;
import com.datastax.driver.core.utils.MoreObjects;
import com.google.common.cache.*;
import com.google.common.reflect.TypeToken;
import com.google.common.util.concurrent.UncheckedExecutionException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.nio.ByteBuffer;
import java.util.EnumMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutionException;

import static com.datastax.driver.core.DataType.Name.*;
import static com.google.common.base.Preconditions.checkNotNull;

/**
 * A registry for {@link TypeCodec}s. When the driver needs to serialize or deserialize a Java type to/from CQL,
 * it will lookup in the registry for a suitable codec. The registry is initialized with default codecs that handle
 * basic conversions (e.g. CQL {@code text} to {@code java.lang.String}), and users can add their own. Complex
 * codecs can also be generated on-the-fly from simpler ones (more details below).
 * <h3>
 * Creating a registry
 * </h3>
 * By default, the driver uses {@link CodecRegistry#DEFAULT_INSTANCE}, a shareable, JVM-wide instance initialized with
 * built-in codecs for all the base CQL types.
 * The only reason to create your own instances is if you have multiple {@code Cluster} objects that use different
 * sets of codecs. In that case, use {@link com.datastax.driver.core.Cluster.Builder#withCodecRegistry(CodecRegistry)}
 * to associate the registry with the cluster:
 * <pre>{@code
 * CodecRegistry myCodecRegistry = new CodecRegistry();
 * myCodecRegistry.register(myCodec1, myCodec2, myCodec3);
 * Cluster cluster = Cluster.builder().withCodecRegistry(myCodecRegistry).build();
 *
 * // To retrieve the registry later:
 * CodecRegistry registry = cluster.getConfiguration().getCodecRegistry();}
 * </pre>
 * {@code CodecRegistry} instances are thread-safe.
 * <p/>
 * It is possible to turn on log messages by setting the {@code com.datastax.driver.core.CodecRegistry} logger
 * level to {@code TRACE}. Beware that the registry can be very verbose at this log level.
 * <h3>
 * Registering and using custom codecs
 * </h3>
 * To create a custom codec, write a class that extends {@link TypeCodec}, create an instance, and pass it to one of
 * the {@link #register(TypeCodec) register} methods; for example, one could create a codec that maps CQL
 * timestamps to JDK8's {@code java.time.LocalDate}:
 * <pre>{@code
 * class LocalDateCodec extends TypeCodec<java.time.LocalDate> {
 *    ...
 * }
 * myCodecRegistry.register(new LocalDateCodec());}
 * </pre>
 * The conversion will be available to:
 * <ul>
 * <li>all driver types that implement {@link GettableByIndexData}, {@link GettableByNameData},
 * {@link SettableByIndexData} and/or {@link SettableByNameData}. Namely: {@link Row},
 * {@link BoundStatement}, {@link UDTValue} and {@link TupleValue};</li>
 * <li>{@link SimpleStatement#SimpleStatement(String, Object...) simple statements};</li>
 * <li>statements created with the {@link com.datastax.driver.core.querybuilder.QueryBuilder Query builder}.</li>
 * </ul>
 * <p/>
 * Example:
 * <pre>{@code
 * Row row = session.executeQuery("select date from some_table where pk = 1").one();
 * java.time.LocalDate date = row.get(0, java.time.LocalDate.class); // uses LocalDateCodec registered above}
 * </pre>
 * You can also bypass the codec registry by passing a standalone codec instance to methods such as
 * {@link GettableByIndexData#get(int, TypeCodec)}.
 * <h3>
 * Codec generation
 * </h3>
 * When a {@code CodecRegistry} cannot find a suitable codec among existing ones, it will attempt to create it on-the-fly.
 * It can manage:
 * <ul>
 * <li>collections (lists, sets and maps) of known types. For example,
 * if you registered a codec for JDK8's {@code java.time.LocalDate} like in the example above, you get
 * {@code List<LocalDate>>} and {@code Set<LocalDate>>} handled for free,
 * as well as all {@code Map} types whose keys and/or values are {@code java.time.LocalDate}.
 * This works recursively for nested collections;</li>
 * <li>{@link UserType user types}, mapped to {@link UDTValue} objects. Custom codecs are available recursively
 * to the UDT's fields, so if one of your fields is a {@code timestamp} you can use your {@code LocalDateCodec} to retrieve
 * it as a {@code java.time.LocalDate};</li>
 * <li>{@link TupleType tuple types}, mapped to {@link TupleValue} (with the same rules for nested fields);</li>
 * <li>{@link com.datastax.driver.core.DataType.CustomType custom types}, mapped to {@code ByteBuffer}.</li>
 * </ul>
 * If the codec registry encounters a mapping that it can't handle automatically, a {@link CodecNotFoundException} is thrown;
 * you'll need to register a custom codec for it.
 * <h3>
 * Performance and caching
 * </h3>
 * Whenever possible, the registry will cache the result of a codec lookup for a specific type mapping, including any generated
 * codec. For example, if you registered {@code LocalDateCodec} and ask the registry for a codec to convert a CQL
 * {@code list<timestamp>} to a Java {@code List<LocalDate>}:
 * <ol>
 * <li>the first lookup will generate a {@code TypeCodec<List<LocalDate>>} from {@code LocalDateCodec}, and put it in
 * the cache;</li>
 * <li>the second lookup will hit the cache directly, and reuse the previously generated instance.</li>
 * </ol>
 * The javadoc for each {@link #codecFor(DataType) codecFor} variant specifies whether the result can be cached or not.
 * <h3>
 * Codec order
 * </h3>
 * When the registry looks up a codec, the rules of precedence are:
 * <ul>
 * <li>if a result was previously cached for that mapping, it is returned;</li>
 * <li>otherwise, the registry checks the list of built-in codecs – the default ones – and the ones that were explicitly
 * registered (in the order that they were registered). It calls each codec's {@code accepts} methods to determine if
 * it can handle the mapping, and if so returns it;</li>
 * <li>otherwise, the registry tries to generate a codec, according to the rules outlined above.</li>
 * </ul>
 * It is currently impossible to override an existing codec. If you try to do so, {@link #register(TypeCodec)} will log a
 * warning and ignore it.
 */

/**
 * 编码解码注册器
 */
public final class CodecRegistry {

    private static final Logger logger = LoggerFactory.getLogger(CodecRegistry.class);

    private static final Map<DataType.Name, TypeCodec<?>> BUILT_IN_CODECS_MAP = new EnumMap<DataType.Name, TypeCodec<?>>(DataType.Name.class);

    static {
        BUILT_IN_CODECS_MAP.put(DataType.Name.ASCII, TypeCodec.ascii());
        BUILT_IN_CODECS_MAP.put(DataType.Name.BIGINT, TypeCodec.bigint());
        BUILT_IN_CODECS_MAP.put(DataType.Name.BLOB, TypeCodec.blob());
        BUILT_IN_CODECS_MAP.put(DataType.Name.BOOLEAN, TypeCodec.cboolean());
        BUILT_IN_CODECS_MAP.put(DataType.Name.COUNTER, TypeCodec.counter());
        BUILT_IN_CODECS_MAP.put(DataType.Name.DECIMAL, TypeCodec.decimal());
        BUILT_IN_CODECS_MAP.put(DataType.Name.DOUBLE, TypeCodec.cdouble());
        BUILT_IN_CODECS_MAP.put(DataType.Name.FLOAT, TypeCodec.cfloat());
        BUILT_IN_CODECS_MAP.put(DataType.Name.INET, TypeCodec.inet());
        BUILT_IN_CODECS_MAP.put(DataType.Name.INT, TypeCodec.cint());
        BUILT_IN_CODECS_MAP.put(DataType.Name.TEXT, TypeCodec.varchar());
        BUILT_IN_CODECS_MAP.put(DataType.Name.TIMESTAMP, TypeCodec.timestamp());
        BUILT_IN_CODECS_MAP.put(DataType.Name.UUID, TypeCodec.uuid());
        BUILT_IN_CODECS_MAP.put(DataType.Name.VARCHAR, TypeCodec.varchar());
        BUILT_IN_CODECS_MAP.put(DataType.Name.VARINT, TypeCodec.varint());
        BUILT_IN_CODECS_MAP.put(DataType.Name.TIMEUUID, TypeCodec.timeUUID());
        BUILT_IN_CODECS_MAP.put(DataType.Name.SMALLINT, TypeCodec.smallInt());
        BUILT_IN_CODECS_MAP.put(DataType.Name.TINYINT, TypeCodec.tinyInt());
        BUILT_IN_CODECS_MAP.put(DataType.Name.DATE, TypeCodec.date());
        BUILT_IN_CODECS_MAP.put(DataType.Name.TIME, TypeCodec.time());
        BUILT_IN_CODECS_MAP.put(DataType.Name.DURATION, TypeCodec.duration());
    }

    // roughly sorted by popularity
    private static final TypeCodec<?>[] BUILT_IN_CODECS = new TypeCodec<?>[]{
            TypeCodec.varchar(), // must be declared before AsciiCodec so it gets chosen when CQL type not available
            TypeCodec.uuid(), // must be declared before TimeUUIDCodec so it gets chosen when CQL type not available
            TypeCodec.timeUUID(),
            TypeCodec.timestamp(),
            TypeCodec.cint(),
            TypeCodec.bigint(),
            TypeCodec.blob(),
            TypeCodec.cdouble(),
            TypeCodec.cfloat(),
            TypeCodec.decimal(),
            TypeCodec.varint(),
            TypeCodec.inet(),
            TypeCodec.cboolean(),
            TypeCodec.smallInt(),
            TypeCodec.tinyInt(),
            TypeCodec.date(),
            TypeCodec.time(),
            TypeCodec.duration(),
            TypeCodec.counter(),
            TypeCodec.ascii()
    };

    /**
     * The default {@code CodecRegistry} instance.
     * <p/>
     * It will be shared among all {@link Cluster} instances that were not explicitly built with a different instance.
     */
    public static final CodecRegistry DEFAULT_INSTANCE = new CodecRegistry();

    /**
     * Cache key for the codecs cache.
     */
    private static final class CacheKey {

        private final DataType cqlType;

        private final TypeToken<?> javaType;

        CacheKey(DataType cqlType, TypeToken<?> javaType) {
            this.javaType = javaType;
            this.cqlType = cqlType;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o)
                return true;
            if (o == null || getClass() != o.getClass())
                return false;
            CacheKey cacheKey = (CacheKey) o;
            return MoreObjects.equal(cqlType, cacheKey.cqlType) && MoreObjects.equal(javaType, cacheKey.javaType);
        }

        @Override
        public int hashCode() {
            return MoreObjects.hashCode(cqlType, javaType);
        }

    }

    /**
     * Cache loader for the codecs cache.
     */
    private class TypeCodecCacheLoader extends CacheLoader<CacheKey, TypeCodec<?>> {
        @Override
        public TypeCodec<?> load(CacheKey cacheKey) {
            checkNotNull(cacheKey.cqlType, "Parameter cqlType cannot be null");
            if (logger.isTraceEnabled())
                logger.trace("Loading codec into cache: [{} <-> {}]",
                        CodecRegistry.toString(cacheKey.cqlType),
                        CodecRegistry.toString(cacheKey.javaType));
            for (TypeCodec<?> codec : codecs) {
                if (codec.accepts(cacheKey.cqlType) && (cacheKey.javaType == null || codec.accepts(cacheKey.javaType))) {
                    logger.trace("Already existing codec found: {}", codec);
                    return codec;
                }
            }
            return createCodec(cacheKey.cqlType, cacheKey.javaType);
        }
    }

    /**
     * A complexity-based weigher for the codecs cache.
     * Weights are computed mainly according to the CQL type:
     * <ol>
     * <li>Manually-registered codecs always weigh 0;
     * <li>Codecs for primitive types weigh 0;
     * <li>Codecs for collections weigh the total weight of their inner types + the weight of their level of deepness;
     * <li>Codecs for UDTs and tuples weigh the total weight of their inner types + the weight of their level of deepness, but cannot weigh less than 1;
     * <li>Codecs for custom (non-CQL) types weigh 1.
     * </ol>
     * A consequence of this algorithm is that codecs for primitive types and codecs for all "shallow" collections thereof
     * are never evicted.
     */
    private class TypeCodecWeigher implements Weigher<CacheKey, TypeCodec<?>> {

        @Override
        public int weigh(CacheKey key, TypeCodec<?> value) {
            return codecs.contains(value) ? 0 : weigh(value.cqlType, 0);
        }

        private int weigh(DataType cqlType, int level) {
            switch (cqlType.getName()) {
                case LIST:
                case SET:
                case MAP: {
                    int weight = level;
                    for (DataType eltType : cqlType.getTypeArguments()) {
                        weight += weigh(eltType, level + 1);
                    }
                    return weight;
                }
                case UDT: {
                    int weight = level;
                    for (UserType.Field field : ((UserType) cqlType)) {
                        weight += weigh(field.getType(), level + 1);
                    }
                    return weight == 0 ? 1 : weight;
                }
                case TUPLE: {
                    int weight = level;
                    for (DataType componentType : ((TupleType) cqlType).getComponentTypes()) {
                        weight += weigh(componentType, level + 1);
                    }
                    return weight == 0 ? 1 : weight;
                }
                case CUSTOM:
                    return 1;
                default:
                    return 0;
            }
        }
    }

    /**
     * Simple removal listener for the codec cache (can be used for debugging purposes
     * by setting the {@code com.datastax.driver.core.CodecRegistry} logger level to {@code TRACE}.
     */
    private class TypeCodecRemovalListener implements RemovalListener<CacheKey, TypeCodec<?>> {
        @Override
        public void onRemoval(RemovalNotification<CacheKey, TypeCodec<?>> notification) {
            logger.trace("Evicting codec from cache: {} (cause: {})", notification.getValue(), notification.getCause());
        }
    }

    /**
     * The list of user-registered codecs.
     */
    private final CopyOnWriteArrayList<TypeCodec<?>> codecs;

    /**
     * A LoadingCache to serve requests for codecs whenever possible.
     * The cache can be used as long as at least the CQL type is known.
     */
    private final LoadingCache<CacheKey, TypeCodec<?>> cache;

    /**
     * Creates a new instance initialized with built-in codecs for all the base CQL types.
     */
    public CodecRegistry() {
        this.codecs = new CopyOnWriteArrayList<TypeCodec<?>>();
        this.cache = defaultCacheBuilder().build(new TypeCodecCacheLoader());
    }

    private CacheBuilder<CacheKey, TypeCodec<?>> defaultCacheBuilder() {
        CacheBuilder<CacheKey, TypeCodec<?>> builder = CacheBuilder.newBuilder()
                // lists, sets and maps of 20 primitive types = 20 + 20 + 20*20 = 440 codecs,
                // so let's start with roughly 1/4 of that
                .initialCapacity(100)
                .maximumWeight(1000)
                .weigher(new TypeCodecWeigher());
        if (logger.isTraceEnabled())
            // do not bother adding a listener if it will be ineffective
            builder = builder.removalListener(new TypeCodecRemovalListener());
        return builder;
    }

    /**
     * Register the given codec with this registry.
     * <p/>
     * This method will log a warning and ignore the codec if it collides with a previously registered one.
     * Note that this check is not done in a completely thread-safe manner; codecs should typically be registered
     * at application startup, not in a highly concurrent context (if a race condition occurs, the worst possible
     * outcome is that no warning gets logged, and the codec gets registered but will never actually be used).
     *
     * @param newCodec The codec to add to the registry.
     * @return this CodecRegistry (for method chaining).
     */
    public CodecRegistry register(TypeCodec<?> newCodec) {
        for (TypeCodec<?> oldCodec : BUILT_IN_CODECS) {
            if (oldCodec.accepts(newCodec.getCqlType()) && oldCodec.accepts(newCodec.getJavaType())) {
                logger.warn("Ignoring codec {} because it collides with previously registered codec {}", newCodec, oldCodec);
                return this;
            }
        }
        for (TypeCodec<?> oldCodec : codecs) {
            if (oldCodec.accepts(newCodec.getCqlType()) && oldCodec.accepts(newCodec.getJavaType())) {
                logger.warn("Ignoring codec {} because it collides with previously registered codec {}", newCodec, oldCodec);
                return this;
            }
        }
        CacheKey key = new CacheKey(newCodec.getCqlType(), newCodec.getJavaType());
        TypeCodec<?> existing = cache.getIfPresent(key);
        if (existing != null) {
            logger.warn("Ignoring codec {} because it collides with previously generated codec {}", newCodec, existing);
            return this;
        }
        this.codecs.add(newCodec);
        return this;
    }

    /**
     * Register the given codecs with this registry.
     *
     * @param codecs The codecs to add to the registry.
     * @return this CodecRegistry (for method chaining).
     * @see #register(TypeCodec)
     */
    public CodecRegistry register(TypeCodec<?>... codecs) {
        for (TypeCodec<?> codec : codecs)
            register(codec);
        return this;
    }

    /**
     * Register the given codecs with this registry.
     *
     * @param codecs The codecs to add to the registry.
     * @return this CodecRegistry (for method chaining).
     * @see #register(TypeCodec)
     */
    public CodecRegistry register(Iterable<? extends TypeCodec<?>> codecs) {
        for (TypeCodec<?> codec : codecs)
            register(codec);
        return this;
    }

    /**
     * Returns a {@link TypeCodec codec} that accepts the given value.
     * <p/>
     * This method takes an arbitrary Java object and tries to locate a suitable codec for it.
     * Codecs must perform a {@link TypeCodec#accepts(Object) runtime inspection} of the object to determine
     * if they can accept it or not, which, depending on the implementations, can be expensive; besides, the
     * resulting codec cannot be cached.
     * Therefore there might be a performance penalty when using this method.
     * <p/>
     * Furthermore, this method returns the first matching codec, regardless of its accepted CQL type.
     * It should be reserved for situations where the target CQL type is not available or unknown.
     * In the Java driver, this happens mainly when serializing a value in a
     * {@link SimpleStatement#SimpleStatement(String, Object...) SimpleStatement} or in the
     * {@link com.datastax.driver.core.querybuilder.QueryBuilder}, where no CQL type information is available.
     * <p/>
     * Codecs returned by this method are <em>NOT</em> cached (see the {@link CodecRegistry top-level documentation}
     * of this class for more explanations about caching).
     *
     * @param value The value the codec should accept; must not be {@code null}.
     * @return A suitable codec.
     * @throws CodecNotFoundException if a suitable codec cannot be found.
     */
    public <T> TypeCodec<T> codecFor(T value) {
        return findCodec(null, value);
    }

    /**
     * Returns a {@link TypeCodec codec} that accepts the given {@link DataType CQL type}.
     * <p/>
     * This method returns the first matching codec, regardless of its accepted Java type.
     * It should be reserved for situations where the Java type is not available or unknown.
     * In the Java driver, this happens mainly when deserializing a value using the
     * {@link GettableByIndexData#getObject(int) getObject} method.
     * <p/>
     * Codecs returned by this method are cached (see the {@link CodecRegistry top-level documentation}
     * of this class for more explanations about caching).
     *
     * @param cqlType The {@link DataType CQL type} the codec should accept; must not be {@code null}.
     * @return A suitable codec.
     * @throws CodecNotFoundException if a suitable codec cannot be found.
     */
    public <T> TypeCodec<T> codecFor(DataType cqlType) throws CodecNotFoundException {
        return lookupCodec(cqlType, null);
    }

    /**
     * Returns a {@link TypeCodec codec} that accepts the given {@link DataType CQL type}
     * and the given Java class.
     * <p/>
     * This method can only handle raw (non-parameterized) Java types.
     * For parameterized types, use {@link #codecFor(DataType, TypeToken)} instead.
     * <p/>
     * Codecs returned by this method are cached (see the {@link CodecRegistry top-level documentation}
     * of this class for more explanations about caching).
     *
     * @param cqlType  The {@link DataType CQL type} the codec should accept; must not be {@code null}.
     * @param javaType The Java type the codec should accept; can be {@code null}.
     * @return A suitable codec.
     * @throws CodecNotFoundException if a suitable codec cannot be found.
     */
    public <T> TypeCodec<T> codecFor(DataType cqlType, Class<T> javaType) throws CodecNotFoundException {
        return codecFor(cqlType, TypeToken.of(javaType));
    }

    /**
     * Returns a {@link TypeCodec codec} that accepts the given {@link DataType CQL type}
     * and the given Java type.
     * <p/>
     * This method handles parameterized types thanks to Guava's {@link TypeToken} API.
     * <p/>
     * Codecs returned by this method are cached (see the {@link CodecRegistry top-level documentation}
     * of this class for more explanations about caching).
     *
     * @param cqlType  The {@link DataType CQL type} the codec should accept; must not be {@code null}.
     * @param javaType The {@link TypeToken Java type} the codec should accept; can be {@code null}.
     * @return A suitable codec.
     * @throws CodecNotFoundException if a suitable codec cannot be found.
     */
    public <T> TypeCodec<T> codecFor(DataType cqlType, TypeToken<T> javaType) throws CodecNotFoundException {
        return lookupCodec(cqlType, javaType);
    }

    /**
     * Returns a {@link TypeCodec codec} that accepts the given {@link DataType CQL type}
     * and the given value.
     * <p/>
     * This method takes an arbitrary Java object and tries to locate a suitable codec for it.
     * Codecs must perform a {@link TypeCodec#accepts(Object) runtime inspection} of the object to determine
     * if they can accept it or not, which, depending on the implementations, can be expensive; besides, the
     * resulting codec cannot be cached.
     * Therefore there might be a performance penalty when using this method.
     * <p/>
     * Codecs returned by this method are <em>NOT</em> cached (see the {@link CodecRegistry top-level documentation}
     * of this class for more explanations about caching).
     *
     * @param cqlType The {@link DataType CQL type} the codec should accept; can be {@code null}.
     * @param value   The value the codec should accept; must not be {@code null}.
     * @return A suitable codec.
     * @throws CodecNotFoundException if a suitable codec cannot be found.
     */
    public <T> TypeCodec<T> codecFor(DataType cqlType, T value) {
        return findCodec(cqlType, value);
    }

    @SuppressWarnings("unchecked")
    private <T> TypeCodec<T> lookupCodec(DataType cqlType, TypeToken<T> javaType) {
        checkNotNull(cqlType, "Parameter cqlType cannot be null");
        TypeCodec<?> codec = BUILT_IN_CODECS_MAP.get(cqlType.getName());
        if (codec != null && (javaType == null || codec.accepts(javaType))) {
            logger.trace("Returning built-in codec {}", codec);
            return (TypeCodec<T>) codec;
        }
        if (logger.isTraceEnabled())
            logger.trace("Querying cache for codec [{} <-> {}]", toString(cqlType), toString(javaType));
        try {
            CacheKey cacheKey = new CacheKey(cqlType, javaType);
            codec = cache.get(cacheKey);
        } catch (UncheckedExecutionException e) {
            if (e.getCause() instanceof CodecNotFoundException) {
                throw (CodecNotFoundException) e.getCause();
            }
            throw new CodecNotFoundException(e.getCause(), cqlType, javaType);
        } catch (RuntimeException e) {
            throw new CodecNotFoundException(e.getCause(), cqlType, javaType);
        } catch (ExecutionException e) {
            throw new CodecNotFoundException(e.getCause(), cqlType, javaType);
        }
        logger.trace("Returning cached codec {}", codec);
        return (TypeCodec<T>) codec;
    }

    @SuppressWarnings("unchecked")
    private <T> TypeCodec<T> findCodec(DataType cqlType, TypeToken<T> javaType) {
        checkNotNull(cqlType, "Parameter cqlType cannot be null");
        if (logger.isTraceEnabled())
            logger.trace("Looking for codec [{} <-> {}]", toString(cqlType), toString(javaType));

        // Look at the built-in codecs first
        for (TypeCodec<?> codec : BUILT_IN_CODECS) {
            if (codec.accepts(cqlType) && (javaType == null || codec.accepts(javaType))) {
                logger.trace("Built-in codec found: {}", codec);
                return (TypeCodec<T>) codec;
            }
        }

        // Look at the user-registered codecs next
        for (TypeCodec<?> codec : codecs) {
            if (codec.accepts(cqlType) && (javaType == null || codec.accepts(javaType))) {
                logger.trace("Already registered codec found: {}", codec);
                return (TypeCodec<T>) codec;
            }
        }
        return createCodec(cqlType, javaType);
    }

    @SuppressWarnings("unchecked")
    private <T> TypeCodec<T> findCodec(DataType cqlType, T value) {
        checkNotNull(value, "Parameter value cannot be null");
        if (logger.isTraceEnabled())
            logger.trace("Looking for codec [{} <-> {}]", toString(cqlType), value.getClass());

        // Look at the built-in codecs first
        for (TypeCodec<?> codec : BUILT_IN_CODECS) {
            if ((cqlType == null || codec.accepts(cqlType)) && codec.accepts(value)) {
                logger.trace("Built-in codec found: {}", codec);
                return (TypeCodec<T>) codec;
            }
        }

        // Look at the user-registered codecs next
        for (TypeCodec<?> codec : codecs) {
            if ((cqlType == null || codec.accepts(cqlType)) && codec.accepts(value)) {
                logger.trace("Already registered codec found: {}", codec);
                return (TypeCodec<T>) codec;
            }
        }
        return createCodec(cqlType, value);
    }

    private <T> TypeCodec<T> createCodec(DataType cqlType, TypeToken<T> javaType) {
        TypeCodec<T> codec = maybeCreateCodec(cqlType, javaType);
        if (codec == null)
            throw notFound(cqlType, javaType);
        // double-check that the created codec satisfies the initial request
        // this check can fail specially when creating codecs for collections
        // e.g. if B extends A and there is a codec registered for A and
        // we request a codec for List<B>, the registry would generate a codec for List<A>
        if (!codec.accepts(cqlType) || (javaType != null && !codec.accepts(javaType)))
            throw notFound(cqlType, javaType);
        logger.trace("Codec created: {}", codec);
        return codec;
    }

    private <T> TypeCodec<T> createCodec(DataType cqlType, T value) {
        TypeCodec<T> codec = maybeCreateCodec(cqlType, value);
        if (codec == null)
            throw notFound(cqlType, TypeToken.of(value.getClass()));
        // double-check that the created codec satisfies the initial request
        if ((cqlType != null && !codec.accepts(cqlType)) || !codec.accepts(value))
            throw notFound(cqlType, TypeToken.of(value.getClass()));
        logger.trace("Codec created: {}", codec);
        return codec;
    }

    @SuppressWarnings("unchecked")
    private <T> TypeCodec<T> maybeCreateCodec(DataType cqlType, TypeToken<T> javaType) {
        checkNotNull(cqlType);

        if (cqlType.getName() == LIST && (javaType == null || List.class.isAssignableFrom(javaType.getRawType()))) {
            TypeToken<?> elementType = null;
            if (javaType != null && javaType.getType() instanceof ParameterizedType) {
                Type[] typeArguments = ((ParameterizedType) javaType.getType()).getActualTypeArguments();
                elementType = TypeToken.of(typeArguments[0]);
            }
            TypeCodec<?> eltCodec = findCodec(cqlType.getTypeArguments().get(0), elementType);
            return (TypeCodec<T>) TypeCodec.list(eltCodec);
        }

        if (cqlType.getName() == SET && (javaType == null || Set.class.isAssignableFrom(javaType.getRawType()))) {
            TypeToken<?> elementType = null;
            if (javaType != null && javaType.getType() instanceof ParameterizedType) {
                Type[] typeArguments = ((ParameterizedType) javaType.getType()).getActualTypeArguments();
                elementType = TypeToken.of(typeArguments[0]);
            }
            TypeCodec<?> eltCodec = findCodec(cqlType.getTypeArguments().get(0), elementType);
            return (TypeCodec<T>) TypeCodec.set(eltCodec);
        }

        if (cqlType.getName() == MAP && (javaType == null || Map.class.isAssignableFrom(javaType.getRawType()))) {
            TypeToken<?> keyType = null;
            TypeToken<?> valueType = null;
            if (javaType != null && javaType.getType() instanceof ParameterizedType) {
                Type[] typeArguments = ((ParameterizedType) javaType.getType()).getActualTypeArguments();
                keyType = TypeToken.of(typeArguments[0]);
                valueType = TypeToken.of(typeArguments[1]);
            }
            TypeCodec<?> keyCodec = findCodec(cqlType.getTypeArguments().get(0), keyType);
            TypeCodec<?> valueCodec = findCodec(cqlType.getTypeArguments().get(1), valueType);
            return (TypeCodec<T>) TypeCodec.map(keyCodec, valueCodec);
        }

        if (cqlType instanceof TupleType && (javaType == null || TupleValue.class.isAssignableFrom(javaType.getRawType()))) {
            return (TypeCodec<T>) TypeCodec.tuple((TupleType) cqlType);
        }

        if (cqlType instanceof UserType && (javaType == null || UDTValue.class.isAssignableFrom(javaType.getRawType()))) {
            return (TypeCodec<T>) TypeCodec.userType((UserType) cqlType);
        }

        if (cqlType instanceof DataType.CustomType && (javaType == null || ByteBuffer.class.isAssignableFrom(javaType.getRawType()))) {
            return (TypeCodec<T>) TypeCodec.custom((DataType.CustomType) cqlType);
        }

        return null;
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    private <T> TypeCodec<T> maybeCreateCodec(DataType cqlType, T value) {
        checkNotNull(value);

        if ((cqlType == null || cqlType.getName() == LIST) && value instanceof List) {
            List list = (List) value;
            if (list.isEmpty()) {
                DataType elementType = (cqlType == null || cqlType.getTypeArguments().isEmpty())
                        ? DataType.blob()
                        : cqlType.getTypeArguments().get(0);
                return TypeCodec.list(findCodec(elementType, (TypeToken) null));
            } else {
                DataType elementType = (cqlType == null || cqlType.getTypeArguments().isEmpty())
                        ? null
                        : cqlType.getTypeArguments().get(0);
                return (TypeCodec<T>) TypeCodec.list(findCodec(elementType, list.iterator().next()));
            }
        }

        if ((cqlType == null || cqlType.getName() == SET) && value instanceof Set) {
            Set set = (Set) value;
            if (set.isEmpty()) {
                DataType elementType = (cqlType == null || cqlType.getTypeArguments().isEmpty())
                        ? DataType.blob()
                        : cqlType.getTypeArguments().get(0);
                return TypeCodec.set(findCodec(elementType, (TypeToken) null));
            } else {
                DataType elementType = (cqlType == null || cqlType.getTypeArguments().isEmpty())
                        ? null
                        : cqlType.getTypeArguments().get(0);
                return (TypeCodec<T>) TypeCodec.set(findCodec(elementType, set.iterator().next()));
            }
        }

        if ((cqlType == null || cqlType.getName() == MAP) && value instanceof Map) {
            Map map = (Map) value;
            if (map.isEmpty()) {
                DataType keyType = (cqlType == null || cqlType.getTypeArguments().size() < 1)
                        ? DataType.blob()
                        : cqlType.getTypeArguments().get(0);
                DataType valueType = (cqlType == null || cqlType.getTypeArguments().size() < 2)
                        ? DataType.blob() :
                        cqlType.getTypeArguments().get(1);
                return TypeCodec.map(
                        findCodec(keyType, (TypeToken) null),
                        findCodec(valueType, (TypeToken) null));
            } else {
                DataType keyType = (cqlType == null || cqlType.getTypeArguments().size() < 1)
                        ? null
                        : cqlType.getTypeArguments().get(0);
                DataType valueType = (cqlType == null || cqlType.getTypeArguments().size() < 2)
                        ? null
                        : cqlType.getTypeArguments().get(1);
                Map.Entry entry = (Map.Entry) map.entrySet().iterator().next();
                return (TypeCodec<T>) TypeCodec.map(
                        findCodec(keyType, entry.getKey()),
                        findCodec(valueType, entry.getValue()));
            }
        }

        if ((cqlType == null || cqlType.getName() == DataType.Name.TUPLE) && value instanceof TupleValue) {
            return (TypeCodec<T>) TypeCodec.tuple(cqlType == null ? ((TupleValue) value).getType() : (TupleType) cqlType);
        }

        if ((cqlType == null || cqlType.getName() == DataType.Name.UDT) && value instanceof UDTValue) {
            return (TypeCodec<T>) TypeCodec.userType(cqlType == null ? ((UDTValue) value).getType() : (UserType) cqlType);
        }

        if ((cqlType != null && cqlType instanceof DataType.CustomType) && value instanceof ByteBuffer) {
            return (TypeCodec<T>) TypeCodec.custom((DataType.CustomType) cqlType);
        }

        return null;
    }

    private static CodecNotFoundException notFound(DataType cqlType, TypeToken<?> javaType) {
        String msg = String.format("Codec not found for requested operation: [%s <-> %s]",
                toString(cqlType),
                toString(javaType));
        return new CodecNotFoundException(msg, cqlType, javaType);
    }

    private static String toString(Object value) {
        return value == null ? "ANY" : value.toString();
    }

}
